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Discussion Starter #1
With identical specs? I understand that there is SUPPOSED to be less friction and faster opening rates for the roller...but does the heavy lifter negate these advantages on the similar sized cam?
 

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As far as I understand, the roller has faster ramp acceleration and although the cams will have similar specs, the roller will act like a much bigger cam, without sacrificing the load power.
 

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Just get a desmodromic roller cam and be done with it you Nascar nut you!

I've wondered about the parasitic HP loss due to the very stiff springs of a roller cam. There must be some additional loss due to this, but the cam's advantages must offset it. If a roller cam didn't have to use stiff valve springs, it would probably really have a big advantage over flat tappet solids.

The mass of the lifters is the primary reason for the stiff valve springs I believe if I remember correctly. You know i'm a big fan of flat tappet solids. They are a good compromise between hydraulic flat and roller.
 

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Hydraulic roller cams have heavy lifters, and aren't very efficient above 6000 rpm. Sure, you can do tricks to get them to rpm a bit higher than that, but a solid works WAY better at those engine speeds.

Hydraulic rollers are great for torquey engines that rarely exceed 6k, but most hotrod 289-302's easily exceed this engine speed, and can benefit from the solid lifters. As a bonus, the flat tappet solid cams are less expensive, and there are no distributer gear issues to worry about.

Lifter acceleration rates of hydraulic rollers and modern flat tappet solid grinds are very close overall, with the solid flats having a major advantage early in the lift cycle. Flat tappet cams are better off the seat anyway. Combine this with the their solid mechanical construction (compared to the relatively spongy hydraulic) and the solid flat kicks hydraulic bootie when accelerating the valve off its seat.

I like flat tappet solids in hotrods.

Good Luck!
_________________
Mike Burch, 66 mustang real street
302 4-speed 289 heads, 10.63 @ 129.3
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
http://www.fortunecity.com/silverstone/healey/367

<font size=-1>[ This Message was edited by: n2omike on 5/8/04 7:41pm ]</font>
 

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Discussion Starter #6
i have the solid flat tappet already Tracy...and no going back
I was just wondering because I was looking at the 514 crate in a past hotrod and it had comparable cam specs to the 520 except that it was a solid roller...a tad more lift but less duration.
 

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Here's my thoughts on it, and I'll explain why I feel this way afterwords.

I don't feel solid rollers are enough of a benefit to justify the cost over a solid flat tappet cam unless; A: your motor is spinning 8000+ rpm, or B: already making in excess of 750 hp.

Here's why I think this. A few years back I was running a solid roller in my racecar. It was running consistantly low 6.40's in the heat of the summer shifting at 7500 rpm (so consistantly in fact, I showed up at the track 3 weeks in a row with the same dial-in on the window; 6.43.) Well, my first time run of this particular weekend the motor sheared the cam pin (something solid roller cammed Ford's are notorious for doing.) Well, I didn't have another roller cam AND lifters (my lifters were all damaged when the cam stopped, the crank didn't, and the pistons met the valves at a high rate of speed.) But, I did have a solid flat tappet that was very similar to the roller. My roller was 264/272 @ .050, .650/.650 lift, 108 lsa. The solid cam was 266/277 @ 050, .625/.623 lift 107 lsa.
Since I was second in points, we didn't have time to get the lifters rebuilt, and I couldn't afford to buy new ones and replace all the bent valves. So instead, I opted to buy new springs and drop the solid cam in. Well, the first pass with it, the car ran the same 60' time it had been, same half track time, SAME ET and mph as it did with the roller. It ran a 6.43 first pass and everyone thought I had put the roller back in. And to top it off, the car ran the quickest 1/4 mile to date with that cam, 9.97.

Oh yeah, this was all in an 11-1 compression iron headed 357 inch cleveland.
 

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Discussion Starter #9
Glad to hear some real world results...from the track to boot! Looks like my motor will produce just as good (and better) than the 514 w/ a roller. Like I said...I was never going to go with a solid roller I just wanted to know if it would make comparable numbers...
Thanks

Jeff Given
 

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Well, now, to throw my opinion in here:

After losing a solid flat cam every year for a couple years during cam break in - requiring complete engine tear down - I will never go back. Solid roller every time from here on out.
 

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I have NEVER lost a solid flat tappet cam during break in.

But I have destroyed a lot of good parts when the pin has sheared in the front of a solid roller cam. It's not worth destroying a thousand dollars worth of parts for 5 hp in my opinion.
 

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Cam profiles is the biggest deciding factor on HP. Roller can run more radical. Such as the Ford roller/hyd that they started using in the 80s Stangs. It's good for emmissions and still makes good HP. A solid roller is very hard on some parts and requires extra building for duriability. Most solid cams will get you where you want to be and cheaper. High HP/RPM 6000-8500 rpms engines I'd pick a roller. Racing/street, solid up 2000 to 7500 rpms. Just my opinion.
 

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That real world anecdote from kid vishis is awesome...it makes me real happy that I decided to use a solid flat tappet cam in my 331. I wish I had about 1-2 weeks to take off from work 'cause I know I could finish my car within that time...to be done after 4.5 years!...wow...I don't know what i'll do with my time...yes I do...get tickets!...no no no...go to car shows and act all wise and stuff...no no no...take my son for a car ride and introduce him to G forces...no no no...he's too young!...I don't know, i'm going to get another glass of wine...to heck with it...too much thinking!
 

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On 2004-05-09 12:16, kid vishus wrote:
I have NEVER lost a solid flat tappet cam during break in.

But I have destroyed a lot of good parts when the pin has sheared in the front of a solid roller cam. It's not worth destroying a thousand dollars worth of parts for 5 hp in my opinion.
I feel the same way about expensive aluminum heads...they are not worth the extra 10-15 HP over properly ported 351w heads with oversize valves on a stret engine that will rarely if ever see more than 6500 rpm...just my opinion, but I plan to make MightyMach a believer when he gets back from spring semester.

Aluminum heads have their place as follows:

1. If you can't port heads
2. If you don't have the tools to port heads.
3. If you building a race motor running above 6500-7000.
4. If you really want to lighten your wallet
5. If you watch too much Horsepower TV or read too much M and F which has lost all creative ability and just promote, promote, promote.
6. If your too young to remember when a whole lot of HP was made from ported iron heads before so many choices were available.
7. If you're tired of blkfrd ranting about "the old days".
 

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Sorry Kidd, but you have to install 2 pins in the front of any solid roller cam....no wonder it broke.

A solid roller will take a more agressive ramp than a solid flat. But what good is a very aggressive profile when you not running the very best of everything else to take advantage of it. When I ordered my solid roller I got one that didn't have the lastest most aggressive profile, I felt that 300+ closed pressure and 600+ open pressure would cause enought trouble.
 

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For the solid flat tappet cams - there are new lifters with a weep hole in the bottom. I don't have the mfg name, but my head guy uses them exclusively and has not had a customer lose a single cam since.
 

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I'm not normally inclined to rain on people's parade's but in this case there are two threads here: solid flat tappet vs. Hydraulic roller and vs. solid roller, not to mention blkfrd's aluminum vs. old school iron heads.

Taken in order the rpm limitations of hydraulic rollers vs. solid flat tappets delimit the range of engine speed comparisons, nver the less the area under the curev carries the day in almost every test you can read given optimized camshafts for both. That is a big assumtion, but if you are after the most performance why wouldn't you make that the basis for the comparison?

If you want to make it a bang for the buck comparison you need to be very clear about intended use, tear down cycles etc. to fairly assess which is better for a given application.

In street/strip applications a solid roller intendned for the street i.e. with appropriate ramps will still significantly ut perform the a solid flat tappet, the question is again bang for buck. The differences are not trivial 10-15 horsepower or for that matter torque curve diffrences. In the case of my big block (again aplles vs. oranges) a hydraulic flat tappet to solid roller of similar duration but more lift was worth a second in quarter mile times. Yes it cost double the flat tappet setup but was it worth it? YES!

You all have to make decisions based on available funds, but don't translate that into solid flat tappet is just as good as any roller. It's simply not the case. If you're not sure look at the bizarre lengths Jon Kaase went to win the big block engine masters challenge with its slid flat tappet requirements. A solid roller would ahve been cheape and more powerful.

I think the after market aluminum head vs. old school iron head is ven more clear, yes you can do ok with well ported old iron heads, but if top power and performance were found that way all the class leaders and high end builders would be using old school iron. Their not. I value doing it yourself as much as anybody but don't confuse saving money with being the fastest or most cost effective when you add up the value of your's or somebody's time.

Flame on.
 

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On 2004-05-10 00:04, Silverliner wrote:

I value doing it yourself as much as anybody but don't confuse saving money with being the fastest or most cost effective when you add up the value of your's or somebody's time.
No flames here. Be forwarned about posters that like to save money will frown upon your response.
 

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Well, some say that aluminum heads are good because they dissipate heat so well, but unfortunately, the less heat that stays in the combustion chamber, the less overall efficiency you get. As percent efficiency is defined as (1-combustion chamber temp/exhaust gas temp)x100, it makes sense that ideally, all heat from the combustion process will stay in the chamber (hence the popularity of thermal coatings) So if you use aluminum heads, if you could make the heads identical in every respect to a pair of iron heads, the iron would outperform the aluminum.

Im not saying that aluminum is bad, as most engines melt when all the heat of combustion stays in the chamber (literally, if all the energy was contained the aluminum pistons would slag) In fact diesels as many know run off of detonation, not spark plugs. The only limiting factor in true power is the fuel preignition. If fuel could withstand any temperature, and only ignite with our express permission when we wanted it too, insane horsepower could be achieved. But issues come up that to make it not preignite, it doesn't burn as well. So it's kind of a catch-22 ideally you want the combustion chamber hotter to contain more energy, and as such need more resistance to detonation, but at the same time that resistance to detonation will hamper the burning of the fuel. It's one of those arguments that can't really be proven by either side, because our true efficiency of car engines is only at something like 25%
 

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Looking at the dollar$ and cent$ side of this in the street strip world has anyone considered "composite lifters"? Composites are more pricey than your standard solid flt but they don't require break in. They also allow for the exchanging of cams like a roller ie no lifter swaps.

Check out:
http://schubeckracing.com/flatsolidframes.html

The issue with sld rollers on the street is the lifters and idiling. Seems to me that if someone wanted to compromise ie not have to worry about wiping out a cam lobe (ie solid flt) OR on the roller side sitting a stop light praying a set of needle bearings don't explode through the hood, then these would be the ticket.

IMHO.
 
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